Remove maintainership

With this patch I remove myself as a maintainer for all packages I
currently maintain.

This is due the fact that I will be basically off the grid from May 2018
until early 2019, as I will be on a trip through north america.

I will revert this patch as soon as I'm back, as I plan to continue
contributing to nixpkgs then.
But as I cannot maintain anything during that time, I'd like to get this
patch merged.

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

pkgs/applications/misc/mdp/default.nix

@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
   meta = with stdenv.lib; {
     homepage = https://github.com/visit1985/mdp;
     description = "A command-line based markdown presentation tool";
-    maintainers = with maintainers; [ matthiasbeyer vrthra ];
+    maintainers = with maintainers; [ vrthra ];
     license = licenses.gpl3;
     platforms = with platforms; unix;
   };